There is a critical gap in the understanding of precisely how synaptic activity leads to the spatial and/or temporal translation of specific synapse-localized mRNAs. The long-term goal of this proposal is to better understand the molecular and cellular mechanisms involved in these processes. With this in mind, the underlying objective of this particular application is to identify and characterize functions for neuronal RNPs (e.g. P-bodies) and RNP components in synaptic mRNA regulation and plasticity processes in vivo. This focus of this proposed work is on Me31B and HPat, two highly conserved P-body and neuronal granule components and regulators of translation. The central hypothesis behind this work is that these core P-body proteins are important regulatory factors controlling miRNA-mediated mRNA translation and plasticity processes in Drosophila neurons. The rationale behind this proposal is based upon the premise that the molecular mechanisms underlying basic forms of learning and memory (and addiction) are highly conserved. It is predicted that Me31B and HPat (e.g. P-bodies) will prove to be new targets for further studies of analogous processes in the normal, non-pathological mammalian CNS and have a positive impact on the treatment of human memory disorders. Therefore, the proposed research is relevant to that part of NIH's mission that pertains to developing fundamental knowledge that will potentially help understand and prevent human disease. This hypothesis will be tested by pursuing two specific aims: 1) to determine to role of P-body components in the regulation of neural plasticity;and 2) to determine the role of P-body components in the regulation of neural mRNA translation. Under the first aim, established assays will be used to determine the ability of Me31B and HPat to regulate general- and miRNA-mediated plasticity processes in two types of "model" neurons in vivo. Under the second aim, established biochemical and genetic techniques will be used to determine the ability of these specific P-body components to: a) interact with the miRNA-RISC (RNA-induced silencing complex) machinery;and b) directly regulate general and/or miRNA-mediated translational repression in vivo. This approach used in this work is innovative because it will draw on: a) structural and functional conservation between P-bodies and neuronal RNPs;and b) an extensive literature base into the function of P-bodies and conserved P-body components. This work is significant because it will provide invaluable insight into a novel molecular mechanisms underlying the regulation of neuroplasticity and, therefore, learning and memory. Moreover, these arguments strongly suggest that this proposed work will have a significant impact on the field of neuroscience. PUBLIC HEALTH RELEVANCE: The proposed studies are in an important and under-investigated area of neural plasticity and have potential applicability to the understanding of the molecular and cellular mechanisms underlying the pathogenesis of memory disorders and addiction. The proposed research has direct relevance to public health, because these mechanisms are evolutionarily conserved. Thus, the findings are ultimately expected to have a significant positive impact on the health of humans.